Intra-fraction respiratory motion and baseline drift during breast Helical Tomotherapy

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• 作者：Rosalinda Ricotti^a ; ^{rosalinda.ricotti@ieo.it} ; Delia Ciardo^a ; Giovanni Fattori^b ; ¹ ; Maria Cristina Leonardi^a ; Anna Morra^a ; Samantha Dicuonzo^a ; ^c ; Damaris Patricia Rojas^a ; ^c ; Floriana Pansini^d ; Raffaella Cambria^d ; Federica Cattani^d ; Chiara Gianoli^b ; ² ; Chiara Spinelli^e ; Marco Riboldi^b ; Guido Baroni^b ; ^f ; Roberto Orecchia^c ; ^g ; Barbara Alicja Jereczek-Fossa^a ; ^c
• 关键词：Intra-fraction motion ; Breast ; Respiratory motion ; Baseline ; Tomotherapy ; Optical tracking system
• 刊名：Radiotherapy and Oncology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：122
• 期：1
• 页码：79-86
• 全文大小：1470 K
• 卷排序：122

文摘

To investigate the intra-fraction breast motion during long-lasting treatments of breast cancer with Helical Tomotherapy by means of an optical tracking system.Materials and methodsA set of seven radio-transparent passive markers was placed on the thoraco-abdominal surface of twenty breast cancer patients and tracked by an infrared tracking system. A continuous non-invasive monitoring of intra-fraction motion from patient setup verification and correction to the end of radiation delivery was thus obtained. The measured displacements were analysed in terms of cyclic respiratory motion and slow baseline drift.ResultsThe average monitoring time per patient was 15.57 min. The breathing amplitude of the chest was less than 2 mm, on average, along all anatomical directions. The baseline drift of the body led to more significant setup uncertainties than the respiratory motion. The main intra-fraction baseline drifts were in posterior and inferior directions and occurred within the first eight minutes of monitoring. Considering the intra-fraction motion only, the resultant clinical-to-planning target volume safety margins are highly patient-specific and largely anisotropic.ConclusionThe non-respiratory motion occurring during prolonged treatments induces notable uncertainties. Non-invasive continuous monitoring of patient setup variations including baseline drifts is recommended in order to minimize dosimetric deviations, which might jeopardize the therapeutic ratio between target coverage and the sparing of organs at risk.